1. Field of the Invention
The present invention relates generally to a bicycle multi-gear hub with a coaster brake. The bicycle can include a hub axle and a hub body enclosing the multi-gear hub. The multi-gear hub can include at least one planetary gear, a coaster brake, and a driver. The planetary gear can include at least one ring gear, a planetary carrier, and at least one sun wheel fixed to the hub axle. A clutch gear can be connected to the driver, so as to be non-rotating but axially movable with respect to the driver.
The clutch gear can form a structural unit with a clutch disc, which clutch disc can establish a drive connection to the planet carrier via engaging dogs on the clutch disc and grooves in the planet carrier. The clutch disc can also establish a drive connection to the ring gear via a longitudinal toothing on the clutch gear and a clutch toothing on the ring gear. The coaster brake can include a brake casing and a brake cone mechanism mounted on a coarse thread of the planet carrier. The cone can be pushed against the brake casing by moving the driver in a braking direction.
2. Background Information
Federal Republic of Germany Patent Application P 37 32 977.4 discloses a multi-gear hub in which a hub body surrounds a hub axle affixed to the bicycle frame, with a driver, a shifting planetary gear and brake mechanism arranged around the hub body. As a five-speed hub, the hub is equipped with a double planet wheel and two sun wheels, which sun wheels can be alternately fixed. Two hill gears and two overdrive gears can be selected. The elements of the planetary gear are shifted by driving either a planet carrier or a ring wheel of the planetary gear to achieve either a hill or overdrive gear ratio. A third speed is achieved as a direct gear by bypassing the planetary gear.
The brake mechanism is actuated by back-pedaling in the braking direction. The torque of the driver is transmitted via a control gear having a driving plate to the planet carrier having a coarse thread, on which a brake cone is pushed beneath a brake casing to spread the same. In overdrive and direct drive, the dogs of the planet carrier are connected with those of the driving plate so as to be non-rotating. In the hill gears, however, the driving plate is connected to the ring gear of the planetary gear. A greater force would thus be applied to the brake mechanism when back-pedaling if the torque directed to the rear were boosted via the planetary gear.
To prevent this and to achieve the same braking effect in all gears, the dogs of the driving plate and those of the ring gear are beveled such that the driving plate is forced axially back into the dogs of the planet carrier when back-pedalling, so that a braking effect in direct translation is achieved as is the case in the overdrive and direct drive gears. The design does not allow for directing the flow of force via the planetary gear to achieve a boosted braking effect on the brake mechanism in all gears. Furthermore, functional problems are to be expected with the engagement of the dogs of the driving plate in the dogs of the planet carrier when back-pedalling because the planet carrier is axially fixed and cannot deflect if the respective dogs meet.